1. Field of the Invention
The present invention relates to a new optical information medium, optical information recording method, and optical information reproducing method, and more particularly to a new optical information medium, optical information recording method, and optical information reproducing method which make it possible to write information optically, and to reproduce information by using an OROM (optical read-only memory) which is a next generation optical disk device.
2. Description of the Related Art
In conventional optical disk devices, signals recorded as a track in a spiral form or tracks in the form of concentric circles on a rotating disk are scanned by a single beam such as a laser beam to read the signals. On the other hand, an OROM (optical read-only memory) which has been presented as a next generation optical disk device comprises a data card as an information medium. The data card has many data regions called patches. Each patch is a two-dimensional image containing 32 KB of data. Also, each patch is divided into grid-like blocks. For each of the data patches, an LED (light emitting diode) and a diffractive lens are provided, and recorded data are reproduced by illuminating the data patches with the LEDs, reading the data images which are collected/reflected and projected through the diffractive lenses on a reflective collector lens and redirected onto a CMOS (complementary symmetry metal-oxide semiconductor field-effect transistor) image sensor, and then digitizing the read images and extracting the recorded data. In the OROM, recorded data can be read while the information medium remains stationary. Therefore, access time is considerably short, that is, 10 ms, and the OROM is strong against mechanical shocks and vibrations. Moreover, the lack of moving parts reduces electric power consumption and it is easy to make the device more compact. Due to these features, much is being expected of the OROM as a next generation optical disk device, and in particular, as an optical disk device for embedded systems and portable equipment which require compactness.
However, these device are read-only devices, and information medium proposed for the OROM are also reproduction-only media.
The data card as a reproduction-only information medium for the OROM has on one side a data layer and on the other side a diffractive lens array layer. This data card is made of a polycarbonate resin, and the data layer and the diffractive lens array layer are formed so as to be integral by injection molding or the like. In order to add information to this information medium, a stamper on which a record signal is recorded is first formed. Thereafter, this stamper is placed at to a molding machine, and then a resin is molded therein to form recording areas on the surface of the resin. However, this process is very long, and debugging cannot be carried out rapidly. Additionally, even when a small number of recording media are manufactured, a long process is necessary for the manufacturing. Thus, much time and cost are required.
An object of the present invention is to provide a new optical information medium which makes it possible to write information optically for rapid debugging or rapid production of a small number of media for small amounts of publication, and makes it possible to reproduce the information by using an OROM which is a next generation optical disk device, and to provide an optical information recording method and an optical information reproducing method using the same.
Focusing on the reading principles of the OROM (optical read-only memory), the present inventors arrived at the present invention.
Namely, an optical information medium of the present invention comprises a substrate, a recordable layer which is formed on one surface of the substrate and which has plural data patches, and a lens layer which is formed on another surface of the substrate and comprises the plural lenses for optically reading of respective data of plural data patches when the data patches are illuminated with light.
It is preferable that a tracking guide is provided at the recordable layer, and recording is carried out by the tracking guide such that the data patches are formed to be divided into grid-like blocks. Further, it is preferable that a means for specifying addresses of the respective blocks is provided on the tracking guide. Moreover, it is preferable that a pitch of the tracking guide is equal to or smaller than a pitch of the respective blocks.
Moreover, an optical information recording method of the present invention comprises the step of irradiating, with recording light, an optical information medium comprising a substrate, a recordable layer which is formed on one surface of the substrate and which has plural data patches, and a lens layer which is formed on another surface of the substrate and comprises the plural lenses for optically reading of respective data of plural data patches when the data patches are illuminated with light, from the recordable layer side so as to record information on the recordable layer. Recording may be carried out while the optical information medium is rotation-driven.
Furthermore, an optical information reproducing method of the present invention comprises the step of irradiating, with reproducing light, an optical information medium comprising a substrate, a recordable layer which is formed on one surface of the substrate and which has plural data patches, and a lens layer which is formed on another surface of the substrate and comprises the plural lenses for optically reading of respective data of plural data patches when the data patches are illuminated with light, from the recordable layer side; and reproducing recorded information by reading transmitted light.